The present invention relates to stabilizing high tonnage ships, such as aircraft carriers and, in particular, stabilization when rolling, that is when listing.
Through the French patent application 2 687 978, filed by the same applicant, a device for stabilizing a ship is known, especially when rolling, using a track on which a train of solid ballast circulates. In fact, referring to FIG. 1 of this document, the stabilizing elements are constituted of two sets or series of rollers 19, rolling on a track constituted, for example, of two lateral rails 25 and 26. A cable 4, driven by a motor 10, through the intermediary of a drive drum 9, makes it possible to displace the rollers 19 from one side to the other of the ship. A blocking system 34, using two jaws 37, is placed between the two sets of rollers 19, and controlled by cable 4. The ensemble is immobilized by closing the jaws 34 against a central positioning rail 30, placed longitudinally above the device. When the cable is not taut, the jaws 34 clamp the central positioning rail 30. In this device, two lateral electric jacks 14 are also used to tighten the cable at its two ends, by the intermediary of a sheave 5, fixed to the pin of the jack. Several such devices can be mounted in parallel in the holds of the same ship, as part of its deck structure.
It is easy to understand that, when the cable is taut, the two clamping jaws 37 separate from each other to free the device relative to the central positioning rail 30. The set of rollers 19 can then be displaced by traction of cable 4, from one side or the other. Suppression of tension, voluntary or provoked by rupture of a strand of the cable 4, automatically blocks the clamping jaws 37 against the central positioning rail 30, in the closest position.
The blocking system used here, in the central part of the assembly, that is in the middle of the two sets of rollers, requires an extremely secure link between the different mobile masses constituted by the rollers. In the same way, the presence of the central blocking rail makes it necessary to envisage rollers 19 of restricted diameter, at least in their central part, to leave a space for the positioning rail 30 to pass through. Because of this, the mass of the assembly is reduced considerably, as well as the efficiency of the system.
In addition, the presence of two electric jacks 14 and their respective mobile sheaves 5 on each side of the system, penalises the system because of their overall dimensions.
The aim of the invention is therefore to remedy these inconveniences, by proposing a different stabilizing device for a ship.
To this end, the main aim of the invention is a stabilizing device for a ship, particularly when rolling, comprising:
a train with a mobile mass rolling on a track;
means for immobilizing the train;
a cable for traction of the train and for controlling the means of immobilization;
a drive means for actuating the cable, and;
means for adjusting the tension of the cable in order to control the means of immobilization, comprising two mobile sheaves to adjust the tension of the cable.
According to the main characteristic of the invention, the means of adjustment also possess a fixed sheave placed on one side of the device, the two mobile sheaves being controlled by a single jack and placed on the other side of the device, opposite the fixed sheave, with the drive means and the jack.
In the preferred embodiment of the means of adjustment, the two mobile sheaves are linked to each other in an elastic fashion, the cable passing around these two mobile sheaves, the drive means being constituted of a winch placed between these two mobile sheaves and around whose drum the cable is rolled.
Advantageously the two strands of cable are fixed in inverse fashion on the winch, around which they roll and unroll, thus alternately and simultaneously.
Preferably, the jack is a hydraulic jack.
In the main embodiment of the invention, it is linked in an elastic fashion to one of the two mobile sheaves.
Advantageously it can be controlled by a solenoid valve.
In the case where means for guiding the train laterally are envisaged, that is with two lateral rails, the means of immobilization essentially comprise a pair of jaws, each pair being controlled by one end of the cable, the jaws of each pair being kept apart from each other by elastic means to come to bear on the lateral rails, their opening being controlled by tension of the cable on these two ends.
In the latter case and when the lateral rails have a standardized I section (IPN), defining two concave parts with three internal surfaces, it is envisaged that the two jaws of each pair of jaws should have three friction surfaces bearing on the three internal surfaces of this winch.
In the case where several stabilizing devices are used on the same ship, it is preferable to envisage, on each winch, means for temporary coupling of the winch with an adjacent device so that, in the event of a breakdown, one of the winches can pull the other.
Advantageously, with the aim of raising the efficiency of the device and, in particular, to optimize the compensation torque provided by the train of mobile mass, the latter should by constituted of lead blocks quasi-parallelepiped in shape, mounted on small wheels rolling on the track.
When the train has to be enclosed in a metallic housing, as imposed by certain requirements concerning high tonnage ships, the track on which these mobile masses roll is constituted by the lower interior surface of the housing, which is installed transversally relative to the axis of the ship.